In the handling of pipes, tubes, rods and other elongated members, a collet or chuck provided on the apparatus is called upon to firmly grasp tubes of different diameters. The collet grasps the tube by employing collet fingers that are radially inwardly compressed against the outer surface of the tube. In order to limit the amount of radial inward travel required of the collet fingers, inserts of varying thickness are used. This effectively enables the tube grasping bore of the collet to have different diameters from which the radial inward contraction begins.
Inserts have been employed in the past which require individual insertion and individual connection, as by means of bolts, for example, to the collet fingers. Such arrangements are undesirable because the time required for making a change. For example, in one arrangement in which individual collet inserts for an automatic pipe bending machine are employed, the separate segments must be individually connected and bolted in place, requiring as much as one minute and one-half for assembly and nearly one minute for removal. Moreover, once removed, the separate collet segments and their bolts must be stored as individual elements on the tool storage shelf and must be individually handled and manipulated for insertion and removal. The time required and the required use of tools for frequent changes of such collet are undesirable in the operation of many machines, such as pipe bending machines, for example.
Accordingly, it is an object of the present invention to provide a collet having a quick change insert assembly that avoids or minimizes problems of the prior art.